1. Technical Field
The present invention relates to a printer having a paper detector mounted on a carriage, and to a paper position detection method of a printer.
2. Related Art
Printing paper is conveyed in a serial printer through a conveyance path past the print position of the printhead, and the position where printing is to start on the printing paper is set to the print position. Thereafter, the printing operation that moves the printhead across the width of the conveyance path perpendicularly to the conveyance direction of the printing paper, and the paper feed operation that conveys the printing paper in increments of a specific conveyance distance through the conveyance path, repeat alternately. The printhead is mounted on a carriage, and the carriage is moved bidirectionally in the transverse direction (widthwise to the conveyance path) by a carriage moving mechanism. Executing a printing process with high positioning precision in a preset print area on the printing paper requires accurately knowing the position of the printing paper when positioning the paper. Serial printers therefore commonly have a paper detector mounted on the carriage so that the paper detector can detect the leading end of the printing paper as it passes the print position, and the position of at least one widthwise edge of the printing paper at the print position.
The paper detector typically has an optical device as the detection part with an emitter that emits a detection beam toward the print position and a photodetector that receives the detection beam reflected from the printing paper. When the printhead of the serial printer is an inkjet head, some of the ink droplets ejected from the printhead may become dispersed as airborne ink mist inside the case before reaching the printing paper.
This ink mist can easily stick to the detection part of the paper detector carried on the carriage, and as the amount of ink mist on the detection part increases, the emitter and the photodetector may become covered with ink and unable to detect the position of the printing paper on the conveyance path when detection is required.
JP-A-2007-130802 discloses technology to suppress the ink mist from sticking to parts inside the case. More specifically, JP-A-2007-130802 teaches putting a fan and a filter inside the case, and capturing ink mist with the filter using the air flow produced by the fan.
Installing a fan and filter for capturing ink mist in a printer obviously requires installation space, and complicates making the printer smaller. A power source for driving the fan is also required, and leads to increasing the manufacturing cost of the printer.